title: Fluids are drugs: type, dose and toxicity.
abstract: OBJECTIVE
  We discuss the formulation of a prescription for intravenous (i.v.) fluid therapy (a 'volume prescription') for critically ill patients: pros/cons of different fluid types; accurate dosing; and qualitative and quantitative toxicities. Updated physiologic concepts are invoked and results of recent major clinical trials on i.v. fluid therapy in the acutely ill are interpreted.
  
  
  RESULTS
  Context is vital and any fluid can be harmful if dosed incorrectly. When contrasting 'crystalloid versus colloid', differences in efficacy are modest, but differences in safety are significant. Differences in chloride load and strong ion difference appear to be clinically important. Quantitative toxicity is mitigated when dosing is based on dynamic parameters that predict volume responsiveness. Qualitative toxicity for colloids (even with newer hydroxyethyl starch 130/0.4 solutions) and isotonic saline remain a concern.
  
  
  CONCLUSIONS
  Similar to any drug used in acutely ill patients, clinicians ordering a volume prescription must recognize that context is crucial. Physiologically balanced crystalloids may be the 'default' fluid for acutely ill patients, and the role for colloids is unclear. Optimal dosing involves assessment of volume responsiveness.
authors.affiliation: Department of Anesthesiology, Duke University Medical Center/Durham VAMC, Durham, North Carolina, USA.
authors.forename: Karthik
authors.initials: K
authors.lastname: Raghunathan
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Shaw
authors.forename: Sean M
authors.initials: SM
authors.lastname: Bagshaw
mesh_terms: D061605:Administration, Intravenous; D003102:Colloids / Q000008:administration & dosage / Q000494:pharmacology; D016638:Critical Illness / Q000628:therapy*; D000077324:Crystalloid Solutions; D005440:Fluid Therapy / Q000379:methods*; D006801:Humans; D007552:Isotonic Solutions / Q000008:administration & dosage / Q000494:pharmacology; D015532:Rehydration Solutions / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology; D012151:Resuscitation / Q000379:methods*; D012306:Risk
chemical_list: D003102:Colloids; D000077324:Crystalloid Solutions; D007552:Isotonic Solutions; D015532:Rehydration Solutions